1. Field of the Invention
The present invention relates to a heat pipe, and more particularly, to a heat pipe which can be used in a case where a conventional heat pipe cannot sufficiently accomplish the task in such a case where a great amount of heat is intended to be conducted, a case of a top heat mode, and a case where heat conduction is performed over a long distance. In actual, such case can be exemplified by that heat accumulated by a solar concentrator mounted on a roof of a house is conducted to an underground heat accumulation tank.
2. Description of the Prior Art
A heat pipe is widely used in various industrial fields since it can conduct heat several hundred times that conducted by a copper rod of the same form. A heat pipe vaporizes inside operating liquid in a high temperature portion thereof, the thus-formed steam is by the steam pressure difference transmitted to a low temperature portion thereof at which the steam is condensed so that heat corresponding to heat of vaporization is quickly transmitted from the high temperature portion to the low temperature portion. The thus-condensed liquid is returned to the high temperature portion by a capillary force generated in a portion called "wick" on the inner wall of the heat pipe.
However, if such a heat pipe is used in a top heat mode (the upper portion of the heat pipe is heated, while the lower portion of the same is cooled in a state where a gravity effects), if an excessive amount of heat is transmitted through the same, or if the same is used for transmitting heat over an excessively long distance, a phenomenon called "burnout" occurs, causing for the heat transmission to be limited or to be prevented. The reason for this lies in that the condensed operating liquid at the low temperature portion of the heat pipe is returned to the high temperature portion by the capillary force of the wick. In the case of the top heat mode, the liquid cannot be supplied to the heights which overcome the capillary force. In the case of the great amount of heat transmission or the long distance transmission, the return of the operating liquid to the high temperature portion can be excessively reduced due to the hydrodynamic resistance of the wick which serves to generate the capillary force. In order to overcome such problems, rotary type heat pipes or electroendosmose type heat pipes can be available. In the rotary type heat pipe, liquid is returned to the high temperature portion by using a centrifugal force generated by rotating the heat pipe formed in a tapered shape. On the other hand, in the electroendosmose type heat pipe, liquid is returned to the high temperature portion by an electric field force generated by applying a high voltage to the heat pipe. However, in these pipes, an individual power source or a electricity needs to be provided outside, or in the case of the long distance transmission, the structure becomes complicated and such type of pipes cannot be actually used.